JP2001345358A - Probe mark depth measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a probe mark depth measuring apparatus capable of simply measuring the depth of a contact mark of a probe in a short time. SOLUTION: An imaging unit 10 images an area including the contact mark of the probe for an electrode part of a semiconductor device 1 after a continuity test, and acquires its image. The imaging is conducted by a CCD camera 15 while using an objective 20 having a numerical aperture NA of 0.15 or less, and the acquired image is transmitted to an image processor 30. The processor 30 processes the image as prescribed such as trimming, an illuminance distribution correcting or the like and then detects the depth of the contact mark of the probe based on image information for the contact mark area such as, for example, an area, dimension, density information and the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a probe mark depth measuring apparatus for measuring a contact mark depth of a probe formed on an electrode in a continuity test of a semiconductor device.

[0002]

2. Description of the Related Art As is well known, a semiconductor device is manufactured by forming a predetermined circuit pattern on a wafer. In a normal semiconductor device manufacturing process, a continuity test is performed after a circuit pattern is formed to check its electrical characteristics. The continuity test is performed by bringing a needle-shaped test probe into contact with an electrode of the semiconductor device.

Generally, the material of an electrode of a semiconductor device is aluminum, which is easily oxidized to form an insulating aluminum oxide (Al ₂ O ₃ ) film on the electrode surface. In order to perform a proper continuity test, it is necessary that a probe penetrates through the aluminum oxide film and contacts a metal part of the electrode during the test.

For this reason, for a semiconductor device determined to be defective in a continuity test, the state of contact of a probe with an electrode has been investigated as one of the causes analysis. In some cases, the state of contact between the probe and the electrode is routinely investigated for all the semiconductor devices subjected to the continuity test.

To determine the quality of the contact state of the probe with the electrode, it is effective to measure the depth of the contact mark of the probe formed by the continuity test. That is, when the depth of the contact mark of the probe is equal to or greater than a predetermined value, it can be determined that the probe has penetrated the aluminum oxide film and has been in good contact with the electrode. It can be determined that there was.

Conventionally, as a device for measuring the depth of a contact mark of a probe, there has been a laser microscope or a micro-roughness measuring device using interference. These devices can move the height position of the observation sample (semiconductor device) and measure the depth of the contact mark of the probe based on optical information obtained at a plurality of different height positions. is there.

[0007]

However, each of the above-mentioned conventional devices is not only expensive, but also requires changing the height position of the sample a plurality of times for one contact mark depth measurement. There is a problem that the measurement takes a remarkably long time. In particular, when routinely examining the contact state of the probe with the electrode, it is preferable that one contact mark depth measurement be as short as possible.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a probe mark depth measuring apparatus capable of easily and quickly measuring the depth of a contact mark of a probe. .

[0009]

In order to solve the above-mentioned problems, the invention of claim 1 is a probe mark depth measuring apparatus for measuring the depth of a contact mark of a probe formed in a continuity test of a semiconductor device. An imaging unit configured to image a region including the contact mark in the semiconductor device; and detecting a depth of the contact mark based on image information on a contact mark region in an image acquired by the imaging unit. A contact mark depth detector.

According to a second aspect of the present invention, in the probe trace depth measuring apparatus according to the first aspect of the present invention, the contact trace depth detecting section detects the depth of the contact trace based on the area of the contact trace region. Is being detected.

According to a third aspect of the present invention, in the probe trace depth measuring apparatus according to the first aspect of the present invention, when the contact trace region has a substantially elliptical shape, the contact trace depth detecting section includes:
The depth of the contact mark is detected based on the major axis of the contact mark area.

According to a fourth aspect of the present invention, in the probe trace depth measuring apparatus according to the first aspect of the present invention, the contact trace depth detecting section includes the contact trace based on density information about the contact trace region. Is detected.

According to a fifth aspect of the present invention, in the probe trace depth measuring apparatus according to the fourth aspect of the present invention, the contact trace depth detector corresponds to a concave portion of the contact trace in the contact trace region. The depth of the contact mark is detected based on the maximum density value of the recessed region.

According to a sixth aspect of the present invention, in the probe mark depth measuring apparatus according to the fifth aspect of the present invention, a stripe pattern in the contact mark area is detected, and the area where the stripe pattern is detected is defined as the concave portion. The apparatus further includes a contact mark shape detection unit serving as an area.

According to a seventh aspect of the present invention, in the probe mark depth measuring apparatus according to the fourth aspect of the present invention, the contact mark depth detecting section includes a contact mark convex portion of the contact mark area. The depth of the contact mark is detected based on the average density value of the corresponding convex region.

According to an eighth aspect of the present invention, in the probe mark depth measuring apparatus according to the seventh aspect of the present invention, a stripe pattern in the contact mark area is detected, and the stripe pattern in the contact mark area is detected. The image forming apparatus further includes a contact mark shape detecting unit that sets a region other than the detected region as the convex region.

According to a ninth aspect of the present invention, in the probe mark depth measuring apparatus according to any one of the first to eighth aspects, the imaging means includes an objective lens having a numerical aperture of 0.15 or less. ing.

According to a tenth aspect of the present invention, in the probe mark depth measuring apparatus according to any one of the first to eighth aspects, the objective means has an aperture near the entrance pupil of the imaging means. A lens, and the aperture has a light-transmitting portion at its optical axis portion and a peripheral portion through which light can pass, and the diameter of the light-transmitting portion of the optical axis portion corresponds to a numerical aperture of 0.15 or less. Is set as follows.

According to an eleventh aspect of the present invention, in the probe mark depth measuring apparatus according to any one of the first to eighth aspects, the objective means has an aperture near the entrance pupil of the imaging means. A lens is provided, the aperture is provided with a transmissive portion through which light can pass, and the transmissivity of the transmissive portion is changed continuously or stepwise from the optical axis of the aperture toward the periphery, and the transmissivity is 5
The diameter of the transmission portion at the position where the transmission ratio becomes 0% is set so that the value corresponding to the numerical aperture is 0.15 or less.

[0020]

Embodiments of the present invention will be described below in detail with reference to the drawings.

<1. Configuration of Probe Depth Depth Measuring Apparatus> FIG. 1 is a diagram showing the overall configuration of a probe trace depth measuring apparatus according to the present invention. This probe mark depth measuring device is a device for examining the contact state of a probe with an electrode by measuring the depth of a probe contact mark after a continuity test, and roughly classifies an area including a probe contact mark in a semiconductor device. The imaging apparatus includes an imaging unit 10 that captures an image and an image processing unit 30 that measures the depth of a contact mark from the image captured by the imaging unit 10.

The imaging section 10 includes an illumination mechanism, an imaging mechanism, and a CCD camera 15 for optically imaging a region including a contact mark in the semiconductor device. As an illumination mechanism, a light source 21, an illumination lens system 22, a half mirror 23, and an objective lens 20 are provided. On the other hand, as the imaging mechanism, an objective lens 20, a half mirror 23, and an imaging lens 25 are provided. The half mirror 23 and the objective lens 20 are shared by both the illumination mechanism and the imaging mechanism.

The light source 21 is a halogen lamp, and the light emitted from the light source 21 is an illumination lens system 2 comprising a plurality of lenses.
After being condensed by 2, the light path is changed by the half mirror 23, and the light enters the objective lens 20. Light emitted from the objective lens 20 is applied to the surface of the semiconductor device 1 formed on the semiconductor wafer W.

The light applied to the semiconductor device 1 is reflected by the surface thereof, and the reflected light passes through the objective lens 20 and the half mirror 23 and is formed by the imaging lens 25 through the CCD camera 15.
Is imaged. The CCD camera 15 is a CCD (charge co
An array of upled devices is provided, and the received light is converted into electric signals to obtain image data.

The semiconductor device 1 after the continuity test as described above
Is captured by the imaging unit 10 and the area is acquired as an image. Here, the numerical aperture NA of the objective lens 20 is set to 0.15 or less and a relatively small value. The reason why the numerical aperture NA of the objective lens 20 is set small is to make it easier to obtain an image of a contact mark by making the light irradiated on the surface of the semiconductor device 1 closer to parallel light. That is,
This is because, when the numerical aperture NA of the objective lens 20 is large, the aperture angle becomes large, and when the contact mark on the surface of the semiconductor device 1 is shallow, it becomes difficult to obtain an image with high contrast. In order to obtain an image with high contrast even when the contact mark is shallow, the numerical aperture NA of the objective lens 20 needs to be 0.15 or less, and preferably 0.1 or less.

The image processing unit 30 is electrically connected to the CCD camera 15, and image data acquired by the imaging unit 10 is transmitted from the CCD camera 15 to the image processing unit 30. FIG. 2 is a block diagram for explaining the configuration of the image processing unit 30. The image processing unit 30 includes a cutout unit 31, an illuminance distribution correction unit 32, and a contact mark region extraction unit 33.
And a contact mark shape detecting section 34 and a contact mark depth detecting section 35. The image processing unit 30 is configured using a computer having a memory, a CPU, and the like. Each processing unit such as the cutout unit 31 is a processing unit realized by the CPU of the image processing unit 30 based on processing software.

The image of the area including the contact marks acquired by the image pickup section 10 is sequentially provided from the cutout section 31 of the image processing section 30 to the illuminance distribution correction section 32, the contact mark area extracting section 33, the contact mark shape detecting section 34, and the contact mark shape. Transmitted to the depth detection unit 35,
A predetermined process is performed on the image in each processing unit. The processing contents of each of these processing units will be described in detail together with the measurement procedure described below.

<2. Probe mark depth measurement procedure> Fig. 3
3 is a flowchart showing a procedure for measuring a depth of a probe mark using the apparatus of FIG. 1. First, with respect to the electrode portion of the semiconductor device 1 after the continuity test, the imaging unit 10 captures an image of a region including a contact mark of the probe, and acquires the image (Step S1). As described above, imaging has a numerical aperture NA of 0.1.
While using the objective lens 20 of 5 or less, the CCD camera 15
The acquired image is transmitted to the image processing unit 30.

Next, the contact mark area is cut out by the cutout section 31 (step S2). FIG. 4 is a diagram for explaining cutting out of the contact mark area. A contact mark area 40 that is an image of a probe contact mark is included in the entire image 41 captured by the imaging unit 10. Cutout part 3
1 cuts out a trimming area 42 of an appropriate size including the contact mark area 40 from the entire image 41. This cutout process is performed for the convenience of each subsequent process, and a rectangular region having a size of about 2 to 3 times the contact mark region 40 is cut out as the trimming region 42. As a specific method, such a difference in shading occurs because a portion where a shading difference is recognized in a region (an area including a predetermined number of pixels) included in the entire image 41 is the contact mark region 40. The cutout section 31 cuts out the periphery of the portion. Further, the trimming area 42 may be cut out visually by an operator of the apparatus. Note that the trimming region 42 is desirably a region only on the electrode metal of the semiconductor device 1, and it is more preferable that a flaw region or the like is excluded by a mask or the like.

When the cutting of the contact mark area is completed, FIG.
In step S3, the illuminance distribution correction unit 32 corrects the illuminance distribution. The correction of the illuminance distribution is a process of obtaining a reference illuminance distribution to quantitatively and accurately obtain density information, which is an important parameter for calculating the depth of the contact mark. Specifically, a histogram of the illuminance values of all the pixels included in the trimming area 42 is created, and the illuminance distribution of the pixels excluding the pixels belonging to the brightest section and the pixels belonging to the darkest section is corrected by first-order approximation. These are defined as a reference illuminance distribution. Here, the reason why the pixels belonging to the brightest section and the pixels belonging to the darkest section are excluded is to remove the influence of irregularities other than the probe contact mark on the electrode surface of the semiconductor device 1.

The correction of the illuminance distribution will be further described with reference to FIG. The solid line in FIG. 5 indicates that the pixel array included in the trimming area 42 has a certain main scanning direction (x
3) is an illuminance distribution of a pixel row for one row (direction). In the pixel column, the pixels belonging to the brightest section and the pixels belonging to the darkest section have been removed. The reference illuminance distribution indicated by the dotted line in FIG. 5 is obtained by correcting (regression analysis) the illuminance distribution indicated by the solid line by first-order approximation. This one
The reference illuminance distribution by the next approximation is represented as “ax + c” (where a and c are constants and a <0 in FIG. 5) when the coordinates of the pixels in the pixel row are represented by x. In the present embodiment, a value obtained by subtracting the actual illuminance value from the illuminance value indicated by the reference illuminance distribution for each pixel in the pixel row (the difference between the solid line from the dotted line in FIG. 5) is defined as the pixel density value. are doing.

In FIG. 5, in order to facilitate understanding of the illuminance distribution correction, one pixel row in a certain main scanning direction has been described as an example. However, the pixel array actually included in the trimming area 42 is planar. Because of this arrangement, the illuminance distribution correction unit 32 performs the same first-order approximation as described above for a planar illuminance distribution. Therefore, the reference illuminance distribution is represented as “ax + by + c” (where a, b, and c are constants) when the coordinates of the pixels in the pixel array of the trimming area 42 are represented by (x, y). Then, the illuminance distribution correction unit 32 sets a value obtained by subtracting the actual illuminance value from the illuminance value indicated by the reference illuminance distribution for each pixel in the pixel array of the trimming area 42 as a pixel density value. If sufficient accuracy cannot be obtained by the first-order approximation for the reference illuminance distribution, a higher-order approximation may be performed.

Since the reference illuminance distribution indicates the general tendency of the illuminance distribution, a pixel region having a high density value (a pixel region having a lower illuminance than the reference illuminance distribution) is darker than its surroundings, for example, a shadow of unevenness. Such an area. Conversely, a pixel area having a low density value (a pixel area having a lower illuminance than the reference illuminance distribution) is an area that is brighter than the surroundings, such as a smooth surface of an electrode with favorable reflection conditions. That is, by calculating the density of the pixel based on the reference illuminance distribution based on the first approximation, it is possible to accurately extract a relative unevenness difference from the periphery as density information.

The density, which is a parameter for calculating the depth of the contact mark, may be logarithmic or may be proportional to luminance as long as a relative unevenness with the surroundings can be grasped. , So-called gamma correction may be performed. In addition, when the measurement process of the contact mark depth is performed by focusing only on the local region where the illuminance distribution can be ignored, the illuminance distribution correction process in step S3 is unnecessary.

Further, the illuminance distribution correction section 32 may perform a smoothing process (so-called blurring process) of the trimming area 42 prior to performing the illuminance distribution correction process. The reason for performing such a smoothing process is to prevent minute irregularities other than probe contact marks from being extracted as density information. Further, instead of performing the smoothing process by the image processing unit 30, the imaging unit 10 may capture the image including the contact mark.
May be optically blurred.

When the illuminance distribution correction processing is performed as described above and the density value of each pixel in the trimming area 42 is calculated based on the reference illuminance distribution, the process proceeds to step S4 in FIG. The extraction processing of the contact mark area is performed by 33. Here, the shape of the probe contact mark formed on the electrode of the semiconductor device 1 during the continuity test will be described.

When the needle-shaped probe comes into contact with the electrode of the semiconductor device 1, the probe breaks through the aluminum oxide film formed on the electrode surface and also digs down the metal part of the electrode. At this time, since the probe slides slightly on the electrode surface, a typical probe contact mark has a substantially elliptical shape. Then, the portion cut and dug down by the probe becomes a concave portion in the contact mark. Since the tip of the probe is not necessarily microscopically flat, a thin groove (scratch) is usually formed in the concave portion by the sliding of the probe. This flaw is formed along the sliding direction of the probe, that is, along the major axis direction of the elliptical shape.
In addition, the portion displaced by the probe rises to the longer-diameter end of the elliptical shape, and the raised portion becomes a convex portion in the contact mark.

As described above, the shape of the probe contact mark often has a substantially elliptical shape composed of a concave portion having a groove formed in the major axis direction and a convex portion protruding at the major axis end. Extract the part. FIG. 6 is a diagram for explaining the contact mark area extraction processing. The trimming area 42 includes an elliptical contact mark area 40 which is an image of the probe contact mark, and the contact mark area extracting unit 33 extracts the contour 46 of the contact mark area 40. That is, the contact mark area extracting unit 33 extracts the elliptical outer part of the contact mark area 40. More specifically, since the contour 46 of the contact trace area 40 has a higher density value than its periphery, pixels having a density higher than a predetermined threshold value than the surrounding area are extracted, and Join together.

Incidentally, in the contact mark area 40, there is a portion having a higher density value than the periphery in addition to the contour portion 46, and a groove portion 47 which is an image of a flaw caused by sliding of the probe is formed. This mainly corresponds to the following (hereinafter referred to as contour 4
A portion where the density value is higher than the periphery, such as 6 and the groove 47, is called an edge). Contact mark area extraction unit 33
Although the groove 47 is recognized as an edge, since the groove 47 does not form a closed region in a substantially elliptical shape, it is ignored in step S4. That is, the contact mark area 40
Is known to have a substantially elliptical shape, and the contact mark region extracting section 33 determines and extracts an edge that becomes a substantially elliptical closed region as the contour 46 of the contact mark region 40.

When the probe contact mark is deep and has an oval shape in a closed area where the edge is clear, it is used as the contour portion 46 as it is. On the other hand, even when the probe contact mark is shallow and the edge does not show a clear elliptical shape in a closed area, a relatively clear edge exists near both ends of the major axis when the contact mark is made elliptical. These may be interpolated and combined to form the contour portion 46. Further, a closed region surrounding the groove 47 which is the edge of the stripe pattern may be used as the contour 46.

A plurality of contact mark areas 40 may exist in the trimming area 42. In such a case, if the contact mark areas 40 are separated from each other or if they can be separated from each other even if they are adjacent to each other, they are separated. Each is treated as one area. On the other hand, when the plurality of contact mark regions 40 are closely adjacent to each other and cannot be separated, a group of adjacent contact marks is treated as one region.

If no edge is found, that is, if it is not possible to extract a portion having a higher density value than the surrounding area by a predetermined threshold value or more, the threshold value is lowered to search for an edge candidate. In this case, it is determined that the contact mark area cannot be extracted, and the process is terminated. In such a case, it can be determined that at least the probe contact mark is considerably shallow.

Further, the probe contact mark itself is the semiconductor device 1
May not be present in a substantially substantially elliptical shape at the ends of the electrodes. In such a case, the process of calculating the contact mark depth based on the major axis and area of the contact mark area 40 described below has no meaning. However, even in such a case, when the convex region 48 of the contact mark region 40 can be completely recognized, the contact mark depth is calculated based on the average density value of the convex region as described later. be able to.

When the contact mark area extraction processing is completed, FIG.
The contact mark shape detection unit 34 calculates the area and dimensions of the contact mark area 40 in step S5. Contact mark area 40
Can be calculated from the number of pixels included in the contact mark area 40 in FIG. The dimensions of the contact mark region 40 are calculated as the major axis and the minor axis of the substantially elliptical contour 46. Note that the dimensions of the contact mark area 40 are
6 may be calculated as the long side and short side of the circumscribed rectangle.

Next, proceeding to step S6 in FIG. 3, the contact mark shape detecting section 34 detects the concave area 45 and the convex area 48 of the contact mark area 40. The concave region 45 and the convex region 48 are images of the concave and convex portions of the probe contact mark, respectively. Since the entire image 41 of the present embodiment is obtained in a planar manner by the imaging unit 10, the concave region 45 and the convex region 48 are distinguished as follows. As described above, a fine scratch is formed in the concave portion of the probe contact mark due to the sliding of the probe.
In FIG. 5, a stripe pattern composed of a plurality of groove portions 47, which is an image of a scratch, is recognized. Then, the plurality of grooves 47 are formed in the contact mark area 40.
Is formed parallel to the major axis direction of the ellipse (the sliding direction of the probe). Therefore, a stripe pattern composed of a plurality of grooves 47 substantially parallel to the major axis of the elliptical shape is detected in the contact mark area 40, and the area where the stripe pattern is detected is defined as the concave area 4
5 and the area other than the concave area 45 is the convex area 4
8 (see FIG. 6).

Next, proceeding to step S7 in FIG. 3, the contact mark depth detecting section 35 detects the depth of the probe contact mark based on the image information on the contact mark area 40. The “image information about the contact mark area 40” is a parameter obtained from an image of the contact mark area 40, and includes the above-described area, size, density information, and the like of the contact mark area 40. Since the density distribution of the density information of the contact mark area 40 is not uniform, there is a combination of what attribute of the density information is focused on which part of which area.

For example, the regions to be noted include a) the entire contact mark region 40, b) the convex portion, c) the entire concave portion, d) the central portion of the concave portion, and e) the end portion of the concave portion. In each of these, the convex side end (upper end of the contact trace area 40 in FIG. 6) is located at position 0 and the concave end (the lower end of the contact trace area 40 in FIG. 6) is located along the major axis direction of the contact trace area 40. If 100, a) the whole (position 0 to position 100),
b) convex part (position 0 to position 20), c) whole concave part (position 3)
0 to position 100), d) central part of the concave portion (position 30 to position 6)
0), e) Attention should be paid to each ratio of the concave end portion (position 70 to position 100).

The portions to be noted in each of the above noted regions are a) the entire region, b) an edge portion, and c).
Non-edge portions and the like are conceivable. As described above, the edge indicates a portion where the density value is higher than the periphery.

Furthermore, what kind of attribute density information should be focused on includes: a) an average density value including positive and negative densities,
Possible candidates are b) an average density value of only the positive density, c) an integrated density value including the positive and negative densities, d) an integrated density value of only the positive density, and e) a maximum density value. The definition of the density value is as described above. Pixels darker than the periphery have a positive density value, and pixels lighter than the periphery have a negative density value. The average density value has a high correlation with the contact mark depth when there is little local variation in the region of interest. On the other hand, the maximum density value has a high correlation with the contact mark depth when there are many local variations in the region to be focused. The integrated density value is a product of the density value and its area.

As a result of intensive studies, the present inventors have found that particularly the following parameters have a high correlation with the contact mark depth.

<2-1. Detection based on major axis> FIG.
FIG. 5 is a diagram showing a contact mark area 40. When the needle-shaped probe contacts the electrode of the semiconductor device 1, the probe slides and digs down the electrode. Therefore, when the probe slides for a longer time, the electrode is dug deeper, and the longer diameter of the substantially elliptical contact mark region 40 (the contour 4
There is a highly correlated proportional relationship between the length ld of the (6 major axis) and the depth of the probe contact mark.

Therefore, the contact mark depth detecting section 35 can estimate the contact mark depth based on the length ld of the major axis of the contact mark area 40 calculated by the contact mark shape detecting section 34.
More specifically, the contact mark area 40 is determined in advance by some experiments.
The proportionality coefficient between the length ld of the major axis of the contact mark and the actual depth of the contact mark is obtained in advance, and the contact mark shape detecting section 34 for the sample to be measured.
Is calculated by multiplying the calculated length ld of the major axis of the contact mark area 40 by the proportional count to detect the depth of the contact mark.

<2-2. Area-Based Detection> The needle-like probe tip is often elongated and conical, and the deeper the probe enters the electrode, the more nearly elliptical contact mark area 40
Area becomes large. That is, there is a high correlation between the area of the contact trace region 40 and the depth of the probe contact trace.

Therefore, the contact mark depth detecting section 35 can estimate the contact mark depth based on the area of the contact mark area 40 calculated by the contact mark shape detecting section 34. Specifically, the correlation between the area of the contact mark region 40 and the actual depth of the contact mark is obtained in advance by some experiments in the same manner as described above, and the contact mark shape detection unit 34 calculates the sample to be measured. The depth of the contact mark may be detected from the area of the contact mark area 40 and the above correlation.

<2-3. Detection Based on Maximum Density Value at Center of Concave> Contact mark shape detecting section 34 determines whether the contact mark area 40 is a convex part or a concave part based on the presence or absence of a striped pattern composed of a plurality of grooves 47. The position 30 to the position where the end on the side determined to be the convex region 48 along the major axis direction of the contact mark region 40 is position 0, and the terminal on the side determined to be the concave region 45 is position 100. The fact that 60 is the central portion of the concave portion is as described above.

The contact mark depth detecting section 35 checks the density value of the pixel along the minor axis direction of the contact mark area 40 at the center of the concave portion as indicated by an arrow A6 in FIG. Detect the value. At this time, usually, the density value of the groove 47 as an edge is detected as the maximum density value. Groove 47
Is an image of a scratch generated by sliding of the probe, which corresponds to the deepest part of the probe contact mark. Therefore, when the maximum density value at the central portion of the concave portion is large, the density value of the groove portion 47 is large, and it is considered that the concave portion of the probe contact mark is deeply damaged, and the maximum density value at the central portion of the concave portion and the depth of the probe contact mark are considered. There is a high correlation between them. The reason for examining the density value of the pixel along the minor axis direction of the contact mark area 40 is that the groove 47 is formed along the major axis direction of the contact mark area 40. This is to make it easy to cross.

As described above, the contact mark depth detecting section 35 can estimate the contact mark depth based on the maximum density value at the center of the concave portion of the contact mark area 40. Specifically, the correlation between the maximum concentration value at the center of the concave portion of the contact mark region 40 and the actual depth of the contact mark is determined in advance by some experiments in the same manner as described above, and the contact mark on the sample to be measured is determined. The depth of the contact mark may be detected from the maximum density value at the center of the concave portion of the region 40 and the above correlation. The maximum density value at the center of the concave portion has a particularly high correlation with the maximum depth of the probe contact mark, and is an effective parameter when it is desired to detect the value.

<2-4. Detection Based on Average Density Value of Protrusion> Contact mark depth detection unit 35 detects the density of pixels along the minor axis direction of contact mark area 40 in protrusion area 48 as indicated by arrow A7 in FIG. Investigate the values and calculate the average concentration value. The protruding portion of the probe contact mark is a protruded portion that is pushed away by the probe at the time of contact, and has a volume substantially equal to the volume of the concave portion. Therefore, the contact mark area 40
The average density value of the convex portion has a high correlation with the depth of the probe contact mark, and it is considered that the probe contact mark is deeper as the average density value is larger.

Accordingly, the contact mark depth detecting section 35 can estimate the contact mark depth based on the average density value of the convex portions of the contact mark area 40. Specifically, the correlation between the average density value of the convex portion of the contact mark area 40 and the actual depth of the contact mark is determined in advance by some experiments in the same manner as described above, and the contact mark area of the sample to be measured is determined. The depth of the contact mark may be detected from the average density value of the 40 convex portions and the above correlation.

FIG. 8 is a diagram showing a correlation between the average density value of the convex portion of the contact mark area 40 and the depth of the probe contact mark.
In the figure, plotted with a + sign is the actual measurement result,
The results of the regression analysis are shown by dotted lines. As shown in the figure, a correlation is recognized between the average density value of the convex portion of the contact mark region 40 and the measured depth of the probe contact mark, and the contact mark depth detection unit 35 expresses the correlation. The depth of the contact mark is detected from the average density value of the convex portions of the sample to be measured based on the regression model indicated by the dotted line.

As described above, in this embodiment, no matter which parameter is used, the simple optical imaging system (imaging unit 10) does not change the sample height position without changing the sample height position.
Contact trace area 40 in the image obtained by the second imaging
Since the image processing unit 30 detects the depth of the probe contact mark based on the image information about the probe, the depth of the probe contact mark can be measured easily and in a short time, and the cost required for the measurement is reduced. Can also be inexpensive. The probe mark depth measuring apparatus of the present embodiment is useful especially when routinely investigating the contact state of the probe with the electrode because the contact mark depth measurement time per operation is short.

<3. Modifications> While the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described examples. For example, in the above-described embodiment, the contact mark area 4 is determined by the presence or absence of the striped pattern including the plurality of grooves 47.
Although it was determined whether it was a convex part or a concave part among 0, the method of determining the concave part convex part is not limited to this. For example, as long as the same probe is used, each of the concave part convex parts is determined. Are almost the same and can be predicted in advance, and thus may be determined based on the prediction. More specifically, for example, the trimming area 42
The upper end of the middle contact mark region 40 may be set as a convex.

The parameters relating to the density information for detecting the depth of the probe contact mark are not limited to those described above. Various combinations can be applied. However, the parameters exemplified above have a relatively high correlation with the depth of the probe contact mark.

In the above embodiment, the imaging unit 1
Although the numerical aperture NA of the objective lens 20 of 0 is set to 0.15 or less, the objective lens 20 may be provided with an aperture 29 as shown in FIG. The aperture 29 is provided at the entrance pupil position in the objective lens 20, and transmission portions 29a and 29b through which light can pass are formed in the optical axis portion and the peripheral portion of the aperture 29, respectively. The transmitting portion 29a is a circular hole, and the transmitting portion 29b is a concentric annular hole. The aperture 29
The region between the transmission portions 29a and 29b is connected to a region outside the transmission portion 29b by a bridging member (not shown).

Here, it is desirable that the position of the transmissive portion 29b around the aperture 29 be determined from the maximum value of the inclination angle of the semiconductor device 1 as the object to be inspected. That is, FIG.
As shown in FIG. 1, assuming that the inclined surface in the probe contact mark is inclined by θ from the horizontal direction, the direction of the reflected light of the light passing through the transmitting portion 29a of the optical axis portion is rotated by 2θ. When the reflected light of the light that has passed through the transmitting portion 29a of the optical axis portion passes through the transmitting portion 29b of the peripheral portion, the reflected light from a portion that should originally be a shadow of unevenness of the contact mark (a portion where reflected light cannot be obtained). Affects the imaging, which is inconvenient. For this reason, even when the inclination angle of the inclined surface in the probe contact mark is the maximum, the reflected light of the light passing through the transmission part 29a of the optical axis part does not pass through the transmission part 29b of the peripheral part. It is desirable to form the transmission part 29b. The diameter of the transmission portion 29a of the optical axis portion is set so that the value corresponding to the numerical aperture NA is 0.15 or less.

In this way, not only the optical axis portion of the aperture 29 but also the peripheral portion can obtain the amount of light through the transmitting portion 29b. Therefore, it is possible to obtain an image with high contrast and to obtain a sufficient amount of light and a sufficient resolving power. And securing can be achieved at the same time.

In the aperture 29 shown in FIG. 9, the peripheral transmission portion 29b is not limited to a single concentric annular hole, but may be a double or more concentric annular hole. With a double or more concentric annular hole, more sufficient light quantity,
High resolution can be obtained. Further, as shown in FIG. 10, the transmission portion 29b in the peripheral portion may be a plurality of circular holes arranged concentrically, instead of a circular hole. A circular hole can be easily formed by a drill or the like, so that the aperture 29 can be easily manufactured.

Further, instead of providing a plurality of transmitting portions in the aperture 29, one transmitting portion through which light can pass is provided, and the transmittance of the transmitting portion is continuously changed from the optical axis of the aperture 29 to the periphery. Alternatively, it may be changed stepwise. Specifically, a hole is formed in the aperture 29, and a flat glass or the like whose transmittance changes continuously or stepwise is fitted into the hole. FIG. 12 is a diagram illustrating a change in transmittance in the transmission section.

In the vicinity of the optical axis of the aperture 29,
The transmittance is high near 100%, and the transmittance continuously decreases toward the periphery. And the transmittance is 5
The diameter of the transmitting portion at the position where the value is 0% is set so that the value corresponding to the numerical aperture NA is 0.15 or less. Note that the transmittance may decrease stepwise toward the periphery.

In this way, a larger amount of light can be obtained as compared with the case where the numerical aperture NA is simply reduced, so that a sufficient amount of light and a sufficient resolving power can be secured while maintaining a high contrast. .

[0071]

As described above, according to the first aspect of the present invention, there is provided an image pickup means for picking up an area including a contact mark in a semiconductor device, and a contact mark area in an image obtained by the image pickup means. A contact mark depth detection unit that detects the depth of the contact mark based on the image information about the probe, so that the depth of the contact mark can be detected by image processing based on the image information. Can be easily and quickly measured.

According to the second aspect of the present invention, since the depth of the contact mark is detected based on the area of the contact mark area, the depth of the contact mark of the probe can be measured more easily and in a shorter time. it can.

According to the third aspect of the present invention, since the depth of the contact mark is detected based on the major axis of the contact mark area, the depth of the contact mark of the probe can be measured more easily and in a shorter time. it can.

According to the fourth aspect of the present invention, since the depth of the contact mark is detected based on the density information on the contact mark area, the depth of the contact mark of the probe is measured more easily and in a shorter time. be able to.

According to the fifth aspect of the present invention, since the depth of the contact mark is detected based on the maximum density value of the concave area of the contact mark area corresponding to the concave section of the contact mark, the contact mark of the probe can be detected. Can be measured simply and in a short time, and particularly the maximum depth of the contact mark can be accurately measured.

Further, according to the invention of claim 6, since the stripe pattern in the contact mark area is detected and the area where the stripe pattern is detected is set as the concave area, the image obtained in a planar manner is Also, the concave region can be easily specified.

According to the seventh aspect of the present invention, the depth of the contact mark is detected based on the average density value of the convex area corresponding to the convex part of the contact mark in the contact mark area. The depth of the contact mark can be measured easily and in a short time.

According to the eighth aspect of the present invention, the stripe pattern in the contact mark area is detected, and the area other than the area where the stripe pattern is detected in the contact mark area is set as the convex area. Even in the acquired image, the convex region can be easily specified.

According to the ninth aspect of the present invention, since the imaging means has the objective lens having a numerical aperture of 0.15 or less, an image having a high contrast can be obtained even when the contact trace of the probe is shallow. .

According to the tenth aspect of the present invention, since the transmission portion through which light can pass is provided in the optical axis portion and the peripheral portion of the aperture of the objective lens, the light amount can be obtained from the transmission portion in the peripheral portion. In addition, a sufficient amount of light and sufficient resolving power can be ensured while obtaining an image with high contrast.

According to the eleventh aspect of the present invention, the transmittance of the transmission portion of the aperture of the objective lens is changed continuously or stepwise from the optical axis of the aperture toward the periphery. A sufficient amount of light and sufficient resolving power can be secured while obtaining a high-contrast image since light can be obtained from the periphery.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of a probe mark depth measuring apparatus according to the present invention.

FIG. 2 is a block diagram for explaining a configuration of an image processing unit in FIG. 1;

FIG. 3 is a flowchart showing a procedure for measuring a depth of a probe mark using the apparatus of FIG. 1;

FIG. 4 is a diagram illustrating cutting out of a contact mark area.

FIG. 5 is a diagram for explaining correction of the illuminance distribution.

FIG. 6 is a diagram for explaining a contact mark area extraction process.

FIG. 7 is a diagram showing a contact mark area.

FIG. 8 is a diagram showing a correlation between an average density value of a convex portion of a contact mark region and a depth of a probe contact mark.

FIG. 9 is a diagram illustrating an example of an aperture of an objective lens.

FIG. 10 is a diagram showing another example of the aperture of the objective lens.

FIG. 11 is a diagram illustrating the determination of the position of a transmissive part in a peripheral part.

FIG. 12 is a diagram illustrating a change in transmittance in a transmission portion of the aperture.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Image pick-up part 15 CCD camera 20 Objective lens 29 Aperture 29a, 29b Transmission part 30 Image processing part 31 Cutout part 32 Illuminance distribution correction part 33 Contact trace area extraction part 34 Contact trace shape detection part 35 Contact trace depth detection part 40 Contact trace Area 45 concave area 48 convex area

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G01R 31/26 G06T 1/00 305Z 5B057 31/28 400D 5C054 G06T 1/00 305 420C 5L096 400 7/60 150J 420 200C 7/60 150 H04N 7/18 C 200 G01B 11/24 F H04N 7/18 G01R 31/28 K (72) Inventor Hiromi Chatani 4-chome Tenjin Kitamachi Kitamachi 1-chome, Horikawa-dori Terunouchi, Kamigyo-ku, Kyoto-shi 1 Dainippon Screen Mfg. Co., Ltd. (72) Inventor Noriyuki Kondo 4-chome Tenjin Kitamachi 1-chome, Horikawa-dori Teranouchi, Kamigyo-ku, Kyoto 1 Dainippon Screen Mfg. Co., Ltd. (72) Inventor Kazutaka Taniguchi 1 Dainichi, 4-chome Tenjin Kitamachi, Kamino-ku, Kyoto F-term in the Screen Manufacturing Company (reference) DJ17 DJ18 DJ23 5B047 AA12 AB02 AB04 BB04 BC05 BC30 5B057 AA03 BA02 BA15 CA08 CA12 CA16 CB12 CB16 CC03 CE04 CE05 CE11 CE20 DA20 DB02 DB09 DC03 DC04 DC16 DC22 5C054 AA05 CA04 CC05 FC12 FC15 FC16 FD01 HA05 FA03 FA06 BA05 FA06

Claims (11)

[Claims] 1. A probe mark depth measuring device for measuring the depth of a contact mark of a probe formed in a continuity test of a semiconductor device, comprising: an imaging unit configured to image a region including the contact mark in the semiconductor device. And a contact mark depth detection unit that detects the depth of the contact mark based on image information about a contact mark area in an image obtained by the imaging unit. Measuring device. 2. The probe mark depth measuring device according to claim 1, wherein the contact mark depth detecting section detects the depth of the contact mark based on an area of the contact mark region. Probe mark depth measuring device. 3. The probe mark depth measuring device according to claim 1, wherein, when the contact mark area is substantially elliptical, the contact mark depth detection unit is configured to determine the contact mark area based on a major axis of the contact mark area. A probe mark depth measuring device for detecting the depth of a contact mark. 4. The probe mark depth measuring device according to claim 1, wherein the contact mark depth detecting unit detects the depth of the contact mark based on density information on the contact mark area. Probe mark depth measuring device. 5. The probe mark depth measuring device according to claim 4, wherein the contact mark depth detecting section is based on a maximum density value of a concave area of the contact mark area corresponding to a concave section of the contact mark. A probe mark depth measuring device for detecting the depth of the contact mark by using the method. 6. The probe mark depth measuring apparatus according to claim 5, wherein a contact mark shape detecting unit that detects a stripe pattern in the contact mark area and sets an area where the stripe pattern is detected as the concave area. A probe mark depth measuring device further provided. 7. The probe mark depth measuring device according to claim 4, wherein the contact mark depth detection unit is configured to calculate an average density value of a convex area of the contact mark area corresponding to a convex part of the contact mark. A probe mark depth measuring device for detecting a depth of the contact mark on the basis of a contact mark. 8. The probe mark depth measuring apparatus according to claim 7, wherein a stripe pattern in the contact mark area is detected, and a portion of the contact mark area other than the area where the stripe pattern is detected is the convex portion. A probe mark depth measuring device, further comprising a contact mark shape detecting section as an area. 9. The probe mark depth measuring apparatus according to claim 1, wherein said imaging means includes an objective lens having a numerical aperture of 0.15 or less. Measuring device. 10. The probe mark depth measuring apparatus according to claim 1, wherein the imaging unit includes an objective lens having an aperture near a position of an entrance pupil, and the aperture includes: The optical axis portion and the peripheral portion have a transmission portion through which light can pass, and the diameter of the transmission portion of the optical axis portion is set so that a value corresponding to the numerical aperture is 0.15 or less. A probe mark depth measuring device characterized by the above-mentioned. 11. The probe mark depth measuring apparatus according to claim 1, wherein the imaging unit includes an objective lens having an aperture near a position of an entrance pupil, and the aperture includes: A transmitting portion through which light can pass; the transmittance of the transmitting portion changes continuously or stepwise from the optical axis of the aperture toward the periphery, and at a position where the transmittance becomes 50%. A probe mark depth measuring apparatus, wherein the diameter of the transmitting portion is set so that a value corresponding to the numerical aperture is 0.15 or less.